It is well-established to manufacture ophthalmic lenses, and in particular contact lenses such as soft contact lenses, in a fully automated manufacturing process. In this process, the contact lenses are typically molded by polymerizing and/or cross-linking a starting material so as to form the contact lens. Depending on the starting material used, it may be required or desired to place the lens in one or more treatment liquids, such as extraction liquids, rinsing liquids and/or coating liquids. Thereafter, the contact lenses are inspected and in case the contact lenses successfully pass the inspection, the lenses are further processed in a packaging unit. In the packaging unit, the contact lenses that have successfully passed the inspection are transferred into packaging shells which, by way of example, may be made of a thermoplastic material, for example polypropylene, through injection molding and which comprise a depression configured to contain a storage solution and a said inspected contact lens.
During packaging, a packaging shell is transferred from a station where packaging shells are provided towards a package holder. Once being placed in the package holder, a contact lens that has successfully passed the inspection step is placed into the depression of the packaging sheet and a storage solution is introduced into the depression, too, so that the contact lens is immersed in the storage solution. Thereafter, a cover film is placed onto the packaging shell containing the contact lens immersed in the storage solution, and the cover film is then thermally sealed to the packaging shell, thereby forming sealed blister packages. After printing information on the cover foil and after a number of possible additional steps, the sealed blister packages are then autoclaved before the autoclaved final blister package is ready for distribution. In the production of large numbers of contact lenses as is the case with disposable contact lenses, it is necessary to be able to manipulate the packaging shells as well as the sealed blister packages safely, quickly and efficiently.
Grippers known in the art for this purpose include a gripper head having vacuum orifices arranged in the gripper head. The gripper head is moved into the depression of the packaging shell, and vacuum is then applied through the vacuum orifices in the gripper head. Once vacuum is applied the wall of the depression adheres to the gripper head, and the packaging shell adhered to the gripper head is transported to and placed on a package holder for supporting the packaging shell during the packaging process. During transportation, packaging shells may slightly move relative to the gripper head, or they may not adhere to the gripper head properly centered, so that upon placing the packaging shell on the package holder (support) breakage of the packaging shell may occur. A broken packaging shell on the package holder (support) cannot be tolerated and must be removed from the package holder and replaced by an undamaged packaging shell, thus reducing the efficiency of the automated process.
Therefore, during gripping and transportation of the packaging shell and during placement of the packaging shell on the package holder, care must be taken to ensure that the packaging shells are correctly positioned and centered.